This week, astronomers discovered another planet: Alpha Centauri Bb. Don’t let the knotty name put you off, or the fact it would take 75,000 years in our fastest rocket to reach it – it is the closest thing to a planet similar to earth. And the world’s astronomers are getting very excited.

One problem, however, is that the surface is thought to be far too hot for life, at about 1,500C. And right now, inside Sir Patrick Moore’s low-ceiling house in West Sussex, the temperature feels about the same.

The swelter is caused by the crush of over-excited astronomers (is that an “observatory” of astronomers or a “nerdery” of star-gazers?), discussing this momentous event. They have been joined by an assorted collection of admirers here to pay homage to King Patrick in his castle, from nine-year-old Jack, who has just started using a telescope, to Brian May, the Queen guitarist and recipient of a PhD for his paper on zodiacal dust.

Ostensibly, the occasion is a book launch – May has collaborated with Moore and the astronomer Chris Lintott on a guide to the universe – but it feels like a very sweaty, rather raucous fans’ convention.

“Patrick inspired us all,’’ May tells me. ''I used to beg to be able to stay up late enough to watch The Sky at Night and I was entranced by him. I was entranced by the idea that there was a seemingly infinite universe out there, and I was entranced by the theme music as well.”

A seven-year-old May first watched Moore on television in the same week he was given his first guitar. For him, asteroids and rock music are connected.

Jon Culshaw, the impressionist, is another guest. “Patrick Moore was my first human impression,” he says. “I’d already cracked Woody Woodpecker, but then I moved onto Patrick. He’s just marvellous.”

We are guzzling back Moore’s Malbec and munching his M&S nibbles in a sitting room crowded with mementoes from his 89 years on this planet. Around 300 shot glasses line the shelves, while pictures of aliens drawn by his mother compete with various globes, a photograph of him at the piano accompanying Albert Einstein, and signed pictures of assorted astronauts. Moore reckons he is the only person to have met the first man to fly, Orville Wright, the first man in space, Yuri Gagarin, and the first man to a walk on the moon, Neil Armstrong.

He has outlived them all. Just. Sadly, he is becoming too frail to party like he used to. And while the temperature continues to rise in the sitting room, a queue is forming outside the study, where Moore is ensconced. Acolytes are allowed in one or two at a time to touch his hem and have him sign their copy of The Cosmic Tourist.

The book, a coffee-table tome of the top 100 sights in the universe, with sumptuous photographs of distant stars and exploding supernovae, is the second venture Moore has undertaken with May and Lintott (the latter was Moore’s co-presenter of the BBC’s The Sky at Night and the only professional astronomer among the three). They are an unlikely trio: May, the badger-loving rock star with Isaac Newton hair; Moore, huge in body and mind despite being in a wheelchair and very frail in speech; and Lintott, who is like a schoolboy hanging out with his heroes.

Lintott is now a tutor at New College, Oxford specialising in how galaxies are formed. He, too, credits Moore with starting it all.

“It was my first year at secondary school, Torquay Boys Grammar, and he came to give a lecture on the outer planets. And I don’t remember anything that he said except for the last few sentences.” He puts on his best Moore rapid-gun, Fifties-type, radio-announcer voice: “ 'I’ve told you about the outer planets, but the truth is we don’t know much about the outer planets and if I come back in 10 years, it will be all different.’ And that was the first time I’d ever heard an adult say we don’t know everything. That was the moment I realised there was science to be done.”

Lintott has been a Moore groupie ever since. Indeed, as an undergraduate, he produced Moore’s “comic opera” (in which Galileo marries the pope). “It was a huge success,” he insists, laughing. “A sell-out, I’ll have you know.”

He is undoubtedly the jolliest of the three. Brian May cuts a rather pensive figure. This may have something to do with the fact he has spent the last hour up in Patrick’s bedroom on the phone to the EU agriculture department, as part of his high-profile quest to stop the Government’s proposed badger cull.

May, who puts on a good-natured act of mock horror when I announce I am from the farmer-friendly Daily Telegraph, says he has hardly slept in the last fortnight as he has shuttled from one meeting to another in Westminster.

His friendship with Moore was formed over Venus and Jupiter, but they also bonded over a mutual love of furry woodland creatures. Moore is a passionate anti-hunt campaigner. What is it about astronomy and animals?

“Contrary to what Ptolemy thought, man is not the centre of the universe,” May begins earnestly. “The earth is not the centre of the universe; it’s not even the centre of the solar system. The solar system isn’t the centre of the galaxy, and the galaxy is not the centre of the observable universe. Man is very small and I think astronomers understand that very well. I don’t think I have ever met an astronomer who didn’t have an empathy for animals.”

Yes, but badgers are spreading TB to cattle; don’t cows get a look-in, too? Here, he fires off a rather dramatic argument against the cull.

“You know we had an Aids epidemic – or so it seemed – in Britain in the Eighties. A number of people had Aids and we were all frightened we were going to get it. So just supposing the Government had said, 'Let’s just kill 70 per cent of people who have Aids’. But it is worse than that, because what they are doing with the badgers is, 'No, let’s kill 70 per cent of all people and see if that improves the situation’. It’s so illogical it actually boggles the mind.”

To me, it is, frankly, a mind-boggling analogy, but he speaks in such a polite, thoughtful tone it is impossible to doubt his sincerity. Does Lintott feel the same?

“All animals are lovely,” he says diplomatically, while making it clear he isn’t going to be picking up a placard any time soon.

Anyway, for him, the most mind-boggling thought of all is that there just might be life out there, following Alpha Centauri Bb’s discovery.

“I would bet you a month’s salary there are more planets in that system.” And what would you bet that some of those planets are in the so-called Goldilocks zone – not too hot, not too cold, where bacteria or plants could survive? “You can have a day’s salary that there are planets with conditions to sustain life.”

Moore chips in, saying: “We can’t be the single one. I am sure of it, but I can’t prove it.”

And, who knows, if we could invent a powerful enough telescope, we might even be able to detect some badgers gallivanting four million light years away. It would certainly make May very happy.